Myths, symbols & folklore
The language of flowers, part seven:

"Especially in the early 19th century, it was not unusual to express difficult messages by means of flower arrangements. A playful flower-symbology had first emerged toward the end of the 18th century, and it was revived a century later. In 1899 G.W. Gessmann wrote that he hoped his guide to this Blumensprache would 'remind especially our gracious ladies of this most sensible custom.' "

Sorrel blossom: "I do not like knowing that you are always following me"
Spurge: "Your nature is so cold that one might think your heart is made of stone"
Sunflower: "It turns ever toward the sun. As sunlight is to it, so is your love to my life."
Thistles: "The poetry of life sweeps over you, leaving no trace"
Thyme: "Unity of souls is the greatest good"
Tulip: "You silent thing of splendor! Where is your inner value?"
Turk's cap: "Will your stirring, roguish glances do much more mischief?"
Vetch flowers: "To be envied are all to whom heaven gives the pearl 'loving friendship'"
Vine leaves: "With your recurring merriment you can restore my high spirits"
Weeping willow: "My heart trembles with the memory of your vanished presence"
Willow: "True friendship presents its arm to us, that we might take it as we walk and bear life's burden"
Yarrow: "Are you in fact as unaware as you would seem?"
(Biedermann)